71 Eldo w/425 exchange from 500 VIBRATTING

1224 Views 14 Replies 4 Participants Last post by carnut, May 28, 2007

cjarvis

Discussion Starter · May 19, 2007 (Edited)

Hello all I switched from the 500 to the 425 everything matched up, but there is a vibration while car is in neutral not at Idle, just at about 2-3k RPM's, and when starting out in drive, seems to mellow down in higher RPM's. The car has 450 miles on it, the guy that rebuilt the engine states that it could be the converter, but it doesnt vibrate in neutral until RPM's are added. How could I troubleshoot with out taking the converter out?

I also wanted to mention that I get a gurgling sound from the block area I have a new water pump, and radiator, hoses and belts, could it be a tension thing? I keep the smog pump as a pully, has anyone put a regular pully on in place of the smog pump? If so please let me know what I need to do to add a regular pully, if anyone has switched one out.

Thanks in advance-Chris

1 - 15 of 15 Posts

the APEMAN

· #2 · May 19, 2007

The clutch fan will do that. Not saying this is your problem just one thing to check.

cadillac_al

· #3 · May 19, 2007

Any chance that a couple plug wires might be crossed? If your running points they might need to be double checked. Just a couple things I would check. I have never had a converter go bad on me in my 30 years of driving; maybe I'm lucky. It seems to me if the converter was causing a vibration it would be felt at any rpm. Good luck.

carnut

· #4 · May 20, 2007

Are the flex plate and harmonic dampner(crank shaft pulley) from the 500 or 425? I'm thinking you used the dampner from the 500 on the 425? or you used the 500's flex plate on the 425. To test the converter, simply unbolt the converter from the flex plate and push the converter back into the trans to clear the flex plate and restart. If I remember, you must remove the sheet metal cover from under the car exposing the converter. I believe the engine is externally balanced and either the dampner or flex plate is causing an unbalanced vibration.

the APEMAN

· #5 · May 21, 2007

500 and 425 flex plate were different looking but completely interchangable.

cjarvis

Discussion Starter · #6 · May 21, 2007

Thanks for the responses, I converted to HEI, I used the 425 flex plate, but either way apeman states they are both interchangable. One thing that I noticed today is that the power steering pump is bad, and is vibrating like crazy, so hopefully when I change that, it will take care of that annoying vibrating, as the pump is indirectly, but directly connected to the motor mounts, so in my opinion it looks like its the ps pump, I'll let you all know.

Thanks

cjarvis

Discussion Starter · #7 · May 21, 2007

The Ape Man said:
The clutch fan will do that. Not saying this is your problem just one thing to check.

How do I check if the clutch fan is working properly or not? Thanks

the APEMAN

· #8 · May 21, 2007

With the engine off give it a spin. If it does not freewheel or feels crusty it is bad.

cjarvis

Discussion Starter · #9 · May 22, 2007

The Ape Man said:
With the engine off give it a spin. If it does not freewheel or feels crusty it is bad.

I may sound stupid on this, but the only think I have attatched to my water pump is the spacer, and the actual fan, it doenst look like I have a clutch fan. Thanks

carnut

· #10 · May 22, 2007

If its just a fixed fan, then remove just it and reattach the spacer only and see if theres a difference? Could be bent?

the APEMAN

· #11 · May 22, 2007

The last 78 Eldorado I had was a '78 with 425 and a clutch fan. Maybe they went cheap on them and used flex fans like the RWD cars of yours could have been swapped somewhere along the way. Dunno. At least that's not the problem. Could still be whacked like the other poster suggests.

cjarvis

Discussion Starter · #12 · May 22, 2007

The Ape Man said:
The last 78 Eldorado I had was a '78 with 425 and a clutch fan. Maybe they went cheap on them and used flex fans like the RWD cars of yours could have been swapped somewhere along the way. Dunno. At least that's not the problem. Could still be whacked like the other poster suggests.

I just noticed that there is a bold missing and when I grab the fan by the spacer I get a little play, so I need to get a bolt for that, would you happen to know the bolt size. Thanks for the suggestions.

carnut

· #13 · May 23, 2007

take one of the three remaining to the hardware store, say, match this!

cjarvis

Discussion Starter · #14 · May 28, 2007

the vibration is still here, i have tightened everything down, new water pump, power steering pump, I still have the old smog pump on there acting as a pully only does anyone know what I need to do to put a regular pully? or how do i measure for a smaller belt that I can run from the crankshaft pully to the water pump? The only thing that I havent tried yet is disconnecting the convereter from the flex plate, would anyone have any suggestions other than that? Thanks

carnut

· #15 · May 28, 2007

To measure for a belt use a length of rope around the pulleys, then measure its length. Belts are listed by length and width.

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